Measuring a Light Neutralino Mass at the ILC: Testing the MSSM Neutralino Cold Dark Matter Model

TL;DR

This paper investigates the potential of the International Linear Collider (ILC) to measure very light neutralino masses within the MSSM, which are relevant for dark matter, by analyzing slepton pair production and decay.

Contribution

It demonstrates that the ILC can accurately measure neutralino masses as low as a few GeV, testing the MSSM dark matter model without relying on grand unification assumptions.

Findings

Mass measurement accuracy for light neutralinos can be around 2 GeV.

ILC can verify or falsify the MSSM neutralino dark matter model for very light neutralinos.

Light neutralino mass measurement is feasible even with slepton masses that are sufficiently light.

Abstract

The LEP experiments give a lower bound on the neutralino mass of about 46 GeV which, however, relies on a supersymmetric grand unification relation. Dropping this assumption, the experimental lower bound on the neutralino mass vanishes completely. Recent analyses suggest, however, that in the minimal supersymmetric standard model (MSSM), a light neutralino dark matter candidate has a lower bound on its mass of about 7 GeV. In light of this, we investigate the mass sensitivity at the ILC for very light neutralinos. We study slepton pair production, followed by the decay of the sleptons to a lepton and the lightest neutralino. We find that the mass measurement accuracy for a few-GeV neutralino is around 2 GeV, or even less if the relevant slepton is sufficiently light. We thus conclude that the ILC can help verify or falsify the MSSM neutralino cold dark matter model even for very light neutralinos.